原油生物降解中含氮化合物δ^(15)N变化原因的实验研究

Experimental research on the causation of crude oil δ^(15)N variation in biodegradation

通过模拟油藏的喜氧环境进行原油微生物降解实验,测定实验降解原油和水样的氮同位素组成,初步探讨了原油生物降解过程中氮同位素变化的原因。实验结果显示,随降解程度增加,原油的氮同位素比值总的变化趋势不断降低,培养液中NH+4的δ15N逐渐增大,暗示微生物在代谢过程中有可能不断利用水溶液中无机化合氮,转化为生物有机氮并部分进入原油,重质组分的增加不仅仅是烃类的优先降解导致的残留和富集。这一现象对于探讨油藏条件下原油微生物降解的作用机理有着一定的实际意义。

The oil biodegradation experiment simulating aerobic circumstance in reservoir was carried out and the nitrogen isotopic ratios of oil and water sam ples were analyzed in order to probe the causation of variation in nitrogen isot opic composition of crude oil. The results show that the trend of ?15N variatio n in oil is decreased and the ?15N of in cultural aqueous phase increased gradu ally with the increase of biodegradation degree, which suggests microorganism ma ke use of inorganic nitrogen compounds from aqueous solution continuously in met abolism and transform to organic nitrogen compounds in oil. So the amount of inc reasing heavier compositions in oil is not only remainder and enrichment caused by the priority degradation of hydrocarbons. The discussion is helpful to unders tanding the mechanism of oil biodegradation under the circumstance in reservoir.